| Authors||Th. van der Hammen, E. Gonzalez|
|Title||Upper pleistocene and holocene climate and vegetation of the “Sabana de Bogota” (Colombia, South America)|
|Journal||Leidse Geologische Mededelingen|
|Abstract||The uppermost 32 metres of a 2436 metre core principally of lake sediments, Pleistocene and Holocene in age from the Sabana de Bogotá were analysed for its pollen content, at intervals of 10—15 cm. About seventy species, genera of families could be recognized, many of them for the first time. The rest of the core is being analysed and the results will be published later. The Sabana de Bogotá lies at an altitude of approximately 2500 metres above sea level, 4½°—5° North of the equator, and 74°—74½° West of Greenwich.|
From the diagram it may be deduced that glacial and interglacial periods affected the tropics equally as Europe and North America. It also shows that the glacial periods were at the same time pluvials, and the interglacials interpluvials.
Curves for the real fluctuations of the tree-line, changes of annual precipitation and changes of temperature have been calculated (fig. 5). Temperatures during the high-glacial phases of the Würm glacial were ± 8° C lower than today, the altitude of the tree-line was some 1300 metres less than now and the snow-line showed an even greater difference (fig. 5).
Radiocarbon dates prove that the parts of the section considered to be respectively Holocene and later Würm-glacial really correspond to those ages. Moreover the temperature curve for the upper Pleistocene of the Sabana de Bogotá corresponds surprisingly well with that published by Emiliani for surface ocean water and by Gross for Europe (fig. 6).
With this knowledge it seemed fully justified to correlate also the older phases with the glacials and interglacials of Europe and North America, using principally the alpine nomenclature. The lowest part of the diagram seems to correspond to the end of Hiss I (= Drenthe stadial), followed by the Riss I—II interstadial, and the Riss II (= Warthe stadial). Then follows the Riss-Würm interglacial, the Würm-glacial (subdivided by two long interstadials, together called Interpleniglacial), and the Holocene.
The more important conclusions of the present study are summarized in paragraph 12.
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